1. Field of the Invention
The present invention relates to a hot isostatic press apparatus in which a material to be processed such as preliminarily shaped metal powder or the like is charged into a high pressure vessel provided with a heater, and the material is pressed and molded by superhigh boosted pressure of fluid or gas medium sealed into the vessel and heating by a heater, making it possible to attain high efficiency of actual production equipment further relates to apparatus in which in stepwise execution of processing operation as required with respect to various materials to be processed including metal material, successive transfer of the material to be processed from one station to the other is automatically performed within a closed operating space still further relates to apparatus for detection of seal leakage in continuous hot isostatic pressing apparatus.
2. Discussion of the Background
A hot isostatic pressing apparatus is known which is one of a number of superhigh press molding technologies and is the so-called HIP apparatus, within which hot isostatic pressing apparatus, a material to be processed, such as preliminarily shaped metal powder, is charged into a high pressure vessel provided with a heater and the interior of which vessel is in a vacuum state or in an active and inactive gas atmosphere, and the material is pressed and molded into a block-like configuration by superhigh boosted pressure of fluid or gas medium sealed into the vessel. Actual production equipment of such apparatus principally comprises a high pressure vessel of a sealed construction in which a part thereof is opened and closed by a cover and the vessel is isolated from the outside by the closure of the cover, as is known. This vessel is merely accompanied by means for opening and closing a cover and means for carrying a material to be processed in and out of the vessel, which means are both exposed to the outside of the vessel, and considerable handling operation is required.
As a heater heretofore used in a high pressure vessel, a heater using an energizing heat generating wire formed of molybdenum group or graphite group material is ordinarily used in a relatively high temperature area. However, such a heater is oxidized (consumed) when it is exposed to the air, and therefore, in removal of a material to be processed, from the high pressure vessel, which is pressed and molded under the sealed condition in the vessel, it is necessary to delay its removal until the heater has been cooled to some degree after high temperature and high pressure have subsided. This naturally involves a longer press cycle time and impairs an increase in productivity. Further, in the antestep of HIP processing, it is necessary to attach a material to be processed to the apparatus at normal temperature and normal pressure and thereafter increase temperature and pressure. This also involves a longer press cycle and impairs productivity.
Furthermore, since the molybdenum group or graphite group heater is oxidized in a high temperature atmosphere, a nonoxidized atmosphere is required or a special atmosphere is required a material to be processed cannot be removed at a high temperature in the atmosphere.
In most cases, a one step operation is not sufficient to form a material to be processed of metal from a blank to a finished product but instead stepwise processing after preliminary molding is required, and in case a hot treatment is applied thereto, heat treatment such as heating is also required. These operations are mostly carried out at respective separate positions and separate places, and therefore, transfer means for blanks and half-finished products for transferring them from one station to the other have to be provided. In the past, in transfer of these materials, conveyors and other transfer means are merely generally used under an atmospheric environment.
For materials to be processed for which specific thermo-environment or atmospheric environment is required, special consideration has to be naturally directed to the transfer means therefor. For example, in the hot isostatic pressing apparatus known as an HIP apparatus which is one of superhigh presses, a preliminarily shaped material to be treated such as metal powder is charged into a high pressure vessel provided with a heater and the interior of the vessel is in a vacuum state or in an active and inactive gas atmosphere, and the material to be processed is pressed and formed into a block-like configuration by a superhigh boosted pressure of fluid (liquid, gas) sealed into the vessel. However, this apparatus principally comprises a high pressure vessel which is isolated from the outside by an openable cover. Means for opening and closing the cover and means for carrying the material to be processed in and out of the vessel are merely provided in a state exposed to the outside of the vessel. As a heater used in the high pressure vessel, a heater using an energizing heat generating wire formed of molybdenum group or graphite group material is ordinarily used. However, the heater of this kind is oxidized (consumed) when it is exposed to the air, and therefore, in removal of a material to be processed, from the high pressure vessel, which is pressed and molded under the sealed condition in the vessel, it is necessary to delay its removal until the heater has been cooled to some degree after the high temperature and high pressure have been reduced. Further, a material to be processed is set in the vessel at normal temperature and normal pressure and thereafter the temperature and pressure are increased. Therefore, this involves a longer press cycle and impairs productivity. In heating a material to be processed in a separate preliminary step, complicated equipment and cumbersome operation are required in terms of time and place according to conventional transfer means. Of course, in not only the HIP apparatuses but apparatus which performs operating steps at separate places and requires a transfer between the respective steps, thus transfer means have to be provided therefor. In materials to be processed wherein such materials need to be placed under a specific thermo-condition and atmospheric environment and wherein members constituting an apparatus which require the aforesaid conditions, are needed conventional transfer means often give rise to inconveniences.
The present applicant is desirous of developing a so-called continuous hot isostatic pressing apparatus which is designed so that a hot isostatic forming high pressure vessel and an operating chamber for inserting or removing a material to be processed are brought into communication with each other by a sealed tank, and the material to be processed is transferred within the sealed tank.
Incidentally, in the continuous hot isostatic pressing equipment as described above, it is extremely difficult for the operating chambers, the high pressure vessel and the sealed tank to be placed under the same pressure and same atmosphere. If the balance of atmospheres is not secured, for example, if when a material to be processed is charged into a sealed tank and transferred, pressure balance between the high pressure vessel, operating chambers and sealed tank is lost, the amount of material to be processed can be reduced or air pressure can possibly blow away a seal material.
In a hot isostatic pressing apparatus for pressing and molding a material to be processed such as metal powder by hot isostatic pressure, an apparatus has been proposed in which operation from insertion to removal of a material to be processed is continuously carried out while being moved from one station to the other.
In the apparatus of this kind, for example, in a main station where a material to be processed is directly pressed and molded, a movable cover with a material to be processed placed thereon is detachably fitted from the lower side thereof into a high pressure vessel, a lower end of which is open to a sealed tank. A seal material on the side where the movable cover is fitted is repeatedly fitted and removed, and as a result, such is liable to be damaged and there is a great possibility of occurrence of seal leakage.
However, in the past, there has not been provided a device for detecting a breakage of the seal material, and accordingly, if such a breakage should occur, high pressure leakage of the sealed tank can lead to breakage of the sealed tank. Because of this, it is necessary to provide a sealed tank which is increased in plate thickness so as not to break the sealed tank even when a seal leakage occurs. This arrangement results in an increase in weight of the sealed tank and thus required a larger-size.
Conversely, if any trouble occurs in a high pressure gas generator for supplying high pressure gas to a high pressure vessel, the high pressure gas back-flows towards the high pressure vessel from the sealed tank so as to thus make it impossible to maintain the atmosphere of the sealed tank.